TOLEDO, Ohio (AP)  Advocacy groups suing the U.S. Environmental Protection Agency over toxic algae in Lake Erie say the agency”s response in court documents bolsters their argument that not enough is being done to protect the lake.

The groups” lawsuit seeks to have the lake”s western basin declared impaired by toxic algae that”s threatening drinking water in Ohio and Michigan. The designation could lead to stricter pollution controls.

In court documents filed last week, the U.S. EPA denies it violated any laws under the Clean Water Act by not including much of Lake Erie on the state”s list of impaired waterways. The agency also said Ohio”s environmental regulators didn”t examine whether Lake Erie”s open waters meet water quality standards.

An Ohio EPA spokeswoman says the lake was evaluated, adding that there”s not enough credible data to determine if open waters are impaired.